Chlorofluorocarbons are compounds widely used as refrigerants' cleaning fluids, propellants and blowing agents for foam manufacture. Despite the versatility of chlorofluorocarbons (CFCs), they have been directly linked to the depletion of the earth's ozone layer. As a result, these compounds are being replaced by hydrofluorocarbon (HFC) compounds and hydrochlorofluorocarbon (HCFC) compounds which do not adversely affect the environment.
Several potential replacements for CFC compounds are 1,1,1,2-tetrafluoroethane also known as HFC-134a, and chlorodifluoromethane (CHClF.sub.2). also known as HCFC-22 Both HFC-134a and HCFC-22 have important uses in refrigeration and cooling systems. As such, HFC-134a has been developed as a replacement r for dichlorodifluoromethane, commonly known as Freon.TM.12.
HFC-134a in particular, may be a good refrigerant replacement since its physical properties (boiling point, molecular weight and nonflammability) are similar to Freon.TM.12. A major disadvantage of using HFC-134a as a refrigerant is that it is not miscible with existing mineral oils and other commonly used lubricants. This poses serious problems in providing a compressor component of a cooling or heating system with proper lubrication.
One reported refrigeration lubricant is a composition of tetrafluoroethane and polyoxyalkylene glycol (see U S. Pat. No. 4,755,316, Magid et al., Jul. 5, 1988). Another lubricant composition for refrigeration compressors comprises a mixture of polyether polyols and esters made from polyhydric alcohols or alkanedioic acids (see U.S. Pat. No. 4,851,144, McGraw and Ward, Jul. 25, 1989).